The Restless EarthThe Structure of the earth:At the centre of the earth, there is a ball of solid ironand nickel called the core. Around the core is themantle, which is semimolten rock that moves veryslowly. The outer layer of the Earth is the crust whichis very thin (approx. 20km). The crust is divided into lots of slabs called tectonicplates they float on the mantle. Plates are made up of two types of crust: oceanicand continental. Continental crust is thinner and less dense oceanic crust isthicker and more dense. The plates are moving because the rock in the mantleunderneath them is moving. Convection currents within the mantle determine thedirection of plate movement. The places where plates meet are calledboundaries or plate margins.4 Types of Plate Margins: 1

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Destructive Margins A destructive margin is when oceanic crust moves towards continental crust, for example the Nazca plate moving towards the South American plate. As the oceanic crust is heavier, it is forced downwards. As it is forced downwards, pressureincreases which can trigger extremely violent earthquakes. At the same time, theheat produced by friction turns the descending crust back into liquid rock calledmagma. This happens in the subduction zone (an ocean trench) zone. Hotmagma tries to rise to the surface.…read more

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Fold MountainsYoung fold mountains are formed along theplate margins where great earth movementstake place.There were long periods of quiet between Earthmovements during which sedimentary rocksthousands of meters thick formed in hugedepressions called geosynclines. Riverscarried sediments and deposited them into thedepressions. Over millions of years the sedimentswere compressed into sedimentary rocks such assandstone and limestone. These sedimentaryrocks were then forced upwards into a series offolds by the movement of tectonic plates.…read more

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Austria and Slovenia. The highest peak is Mont Blanc near the FrancoItalianborder at 4810 meters, but there are many other peaks above 3800 meters.Human activity...Farming & Forestry: Most farms are located on the sunnier and warmersouthfacing slopes. The traditional pattern of farming is dairy farming using asystem called transhumance, the seasonal movement of animals.…read more

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Hydroelectric power (HEP) and Industry: The steep slopes, highprecipitation and summer melting of the glaciers produce fastflowing rivers thatare ideal for generating HEP. The narrow valleys are easy to dam and there arelakes in which to store water. Some of the cheap HEP is used by industries whichrequire a high input of electricity such as sawmills, electrochemicals and fertilisermanufacture and aluminium smelting. Some of the electricity is also exported toother regions to supply towns and cities.Population...…read more

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Volcanoes are divided into two main types, depending upon the material thrownout in an eruption and the form (height and shape) of the volcanic cone produced: Type Shield Composite Cone Plate margin Constructive Destructive Formation As the plates move apart, When the plates collide, the magma rises to fill the denser oceanic plate is gap. This adds new rock pushed down into the mantle. to the spreading plates.…read more

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Examples Hekla & Surtsey, Iceland Etna & Vesuvius, Italy Mauna Loa & Kilauea, Krakatoa, Indonesia Hawaii Mount St. Helens, USA Nyriagongo, the Congo (Africa)Why people live near volcanoes...It has been estimated that 500 million people now live in areas that are likely to beaffected by earthquakes and volcanic eruptions. People are even migrating therewith this knowledge and the populations of some of these places are increasing.The main reasons...…read more

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Other reasons:They may believe that they are safe to be near a volcano that has been dormantfor a long timeIt is much cheaper to live in these areas and people may not be able to afford tolive anywhere elseThey trust the scientific information and feel adequately preparedThey have always lived here and do not want to break family traditionsFor many people it would seem that the advantages of living in a danger zone faroutweigh the risk of…read more

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Residents had been told to leave and visitors were not allowedinside an 8km exclusion zone around the crater.The expected, yet unpredictable, eruption happened at 8:32am on 18th May.An earthquake measuring 5.1 on the Richter scale caused a landslide on thenortheast side of the mountain. This was the biggest landslide ever recorded andthe sideways blast of pulverised rock, glacier ice and ash wiped out all livingthings up to 27km north of the crater.…read more